I don't think the role of the critic has changed very much. In the most positive sense, the music critic is one who helps the public navigate what's out there, especially in bringing attention to things they otherwise wouldn't hear about, or to provide a new window into something familiar.
Michael HerschI think the tendency to paint composers or styles of music with too broad a brush - for example, identifying composers as writers of "simple" or "complex" music - has become increasingly problematic and is almost never productive.
Michael Hersch